Harris et al. in European patent application No. 46,289 disclose that various substituted enantholactam derivatives possess angiotensin converting enzyme inhibition activity.
Harris et al. in European patent application No. 46,291 disclose that various substituted caprolactam derivatives possess angiotensin converting enzyme inhibition activity.
Harris et al. in European patent application No. 46,292 dislcose that various substituted caprylolactam derivatives possess angiotensin converting enzyme inhibition activity.
Meyer et al., "Angiotensin Converting Enzyme Inhibitors:modifications Of A Tripeptide Analogue", J. Med. Chem., 1982, 25, 996-999, disclose the synthesis and activity of compounds of the formula ##STR3## wherein X can be NH and R and be L-proline.